Electric switch



Aug. 10, 1943. R. H. KINGDON ELECTRIC SWITCH 3 Sheets-Sheet 1 Filed Feb. 27, 1941 INVENTOR R a I 1; H. Kz'rglon a RNEY 1943. R. H. KINGDOM) 2,326,299

ELECTRIC SWITCH Filed Feb. 27, 1941 3 Sheets-Sheet 3 INVENTOR RZYZ II. z'iz lon ment of the parts.

Patented Aug. '10, 1943 ELECTRIC SWITCH Ralph H. Kingdon, Detroit, Mich., assignor to Square D Company, Detroit,

, tion of Michigan Mich. a corpora- Application February 27, 1941, Serial No. 380,841

13 Claims.

This invention relates to electric switches, and more particularly to manually operated electric switches in which the switching element is operated to itsswitching positions with a snap action. V

One object of theinvention is a manually operated' electric switch with overcenter spring mechanism for actuating the switch to its operating positions with asnap action provided with means preventing the mechanism from having a dead center position.

Another object of the invention is to provide a manually operated electric switch having overcenter spring mechanisms for providing the switch with a' snap action in which the only stable position of the operating mechanism will In electric switches of the manually operated overcenter spring, snap-acting type, particularly in the rather heavy industrial switches utilizing knife blade and jaw contacts, it has been found that it is sometimes possible to place the parts in a dead center position in which they are semistable without being either in the true "on or true oii position. The parts of the operating mechanism of these switches are made to rather wide tolerances and it sometimes occurs that a rather broad dead center position results which is efiective over a relatively wide arc of move- In'going from the on to the 01f position, it is possible for the parts to reach this semi-stable, dead center position while the v contacts are still engaged and with the operating handle out of the on position. If the switch were left in this position, a casual inspection of the exterior would, from the position of the operating handle, indicate that the circuit was open through the switch, whereas in fact the circuit is still closed and a dangerous condition is thus produced if an attempt is made to work on the live circuit closed through the switch. On the other hand, in going from the off to the on position, this semi-stable dead center position of the parts might be reached with the contacts remaining separated and a subsequent jarring or other causes efiect movebe' the full on and full ofi positions of the- .one end in the left side wall ment of the parts from the semi-stableinto the on position with closing of the circuit with possible dangerous results. The object of this invention is to avoid the occurrence of the semistable dead center position in manually operated electric switches using overcenter spring oper-- ating mechanisms so that both the switching parts and the operating handle will always be in full on or full off position; and, hence, it will be impossible to place the parts in any semistable intermediate position.

Other objects and features of the invention will be readily apparent to those skilled in the art from the specification and appended draw- .ings illustrating certain preferred embodiments of the invention in'which:

Figure 1 is a front elevational view of an electric switch according to the present invention with the front cover broken away to show inter-' nal parts,

Figure 2 is a vertical sectional view showing the operating mechanism for the switch.

Figure 3 is a partial horizontal sectional view of the operating mechanism.

Figure 4 is a vertical view similar to Figure 2 but with the parts in a different operating position.

Figure 5 is an enlarged view part of the mechanism. L

Figure 6 is a view of the operating part of Figure 5 taken in the direction of the arrow. VI.

Figure 7 is a view of the operating part of Figure 5 taken in the direction of the arrow VII.

Figure 8 is a view similar to Figure -5 but of a modified arrangement for the operating part.

The electric switch of the present invention comprises a sheet metal enclosing box I having an openable cover 2 hingedly mounted thereon. Within the box, the switching parts comprise of an operating stationary jaw contact members 3 and knife blades lhingedly mounted in jaws ,5. Below the contacts are disposed pairs of fuse clips 6 and I for the inclusion in the circuit of circuit protecting fuses. The knife blades 4 are connected by means of straps 8 to a common insulating bar 9 which is, in turn, connected through the links H to an operating bail l2 pivotally mounted at of the box and pivoted at its other end as will be hereinafter described.

Upon the back wall of the box is secured an L-shaped bracket I3 provided with an opening which, in conjunction with an opening in the right hand side wall of the box, serves to pivot the operating handle l4, having an exterior grip- .10. to this dead center spring 26 moves through its ping portion I5 and an interior horizontal portion It. Keyed upon the interior end of the operating handle for movement therewith is an operating finger I! having a fiat opening receiving the flattened end of the operating handle so as to be rigidly moved therewith, this keying being shown iIyF'igures 2 and 4. Upon the horizontal portion it of the operating'handle is rotatably mounted an element i8 shown more in' detail in Figures 5, 6, and 7, the element l8 having keyed therewith a bushing is upon the exterior surfaceof which at the left hand side, as viewed in Figure 3, the end of the operating bail I2 is looped and pivotally mounted. The element I8 is provided with a pair of spaced integral lugs 2| and 22 between which are disposed both the finger I1 and the arm 23 of the bail I2.

center position provides a hammer blow which positively overcomes the remaining friction between the jaws 3 and blades 4 to ensure their proper separation.

The -operation of the parts from the oif position of Figure 4 to the 6n" position'of Fig-' ure 2 is Just the reverse of that previously described; and in view of the obtuse angle formed by the slot 28. the pin 21 will again move within the slot as the spring approaches its dead center I position and will throw the spring through its Upon the right hand side wall 01 the box is pivotally mounted a guide bracket 24 having a slot therein through which extends a spring guide 25, about which is coiled the operating spring 26.

The opposite end or the spring guide i secured to the element It by means of a pin 21 connected to the guide and disposed in a slot 28 in the element 18. This slot is in the form or an obtuse angle and the pin 21 isadapted to slide therein. A second slot 29 is provided at the opposite end oi the element l8 and this is 1 to be used with a duplicate spring guide and overcenter spring in case a greater operating force is desired.

In the operation of the switch, it is seen that the placing of finger I'I between lugs 2| and 22 provides for a lost motion connection between the operating handle and element I8, and the placing of the arm 23 of bail l2 between the lugs 2| and 22 provides a second lost motion between the element l8 and the operating bail I2. As the handle is pulled downwardly from the position of Figure 1, finger l1 engages lug 22 to rotate element I8 in a clockwise direction, as viewed in Figure 2, against the force exerted by spring 26. The initial movement of the element I8 is efiected without moving-the bail l2, but after it has moved through a certain distance, the lug 2| engages the arm 23 of bail l2 and ef- :lfects positive movement of the hail from the now positive connection with the operating handle in the clockwise direction. At this time, the blades 4 will start their movement out of contact laws 3. Just prior to the time when the blades 4 leave the jaws 3, the spring 26 will snap overcenter and will thereupon apply its bias to continue the rotation of the element l8 in a clockwise direction, thus quickly snapping. the blades 4 out of the jaws 3 and into their full "of!" position with the parts being then related as shown in Figure 4. i

with the invention herein disclosed. at a certain angle prior to the actual dead center line of spring 26, say, for, example, at an angle of line, the angle of slot 28 with respect to the direction of force exerted on spring guide pin 21 becomes such as to eflect movement of the pin within the slot so that dead center position irrespective of further movement of the member I8 toward operating position. This occurs a sufficient distance prior to the actual dead center position and throws the spring a sufllcient distance through the dead center position, so that it is impossible to effect a maintenance of the operating parts in dead center position. Furthermore, the sudden stopping of pin 2'! in the slot after it has moved the spring through dead |8 is therein provided with a straight slot 3| adapted to receive the spring guide pin 21. In view of the straight line characteristic of this slot, the movement of the pin therein'occurs only in one direction so that the movement of the spring through its dead center position irrespective of the movement of the element It occurs only in one direction. Such a slot could be used to operate in either direction but would normally be utilized to move the spring through dead center position in moving from o to off positions to ensure proper opening of the switch. However, the obtuse angle slot of the preferred embodiment is the preferred form of the invention as it provides for movement of the point of attachment of the spring in both directions of operation and, hence, prevents the maintaining of parts in a dead center position in both directions of operation of the switch.

While certain preferred embodiments of the invention have -been specifically disclosed, it is understood that the invention is not limited thereto, as many variations will be readily apparent to those skilled in the art and the invention is to be given its broadest possible interpretions to both the handle and bail, an overcenter spring connecting to said interconnecting means,

' and means for effecting movement of the point of spring connection to the interconnecting means independent of movement of the interconnecting means when the overcenter spring has been movedto a predetermined position so as to effect movement of the overcenter sprin throughits dead center position independent of movement of the operating handle.

2. In an electric switch, cooperating stationary and movable contacts, operating means connected to the'movable contacts, an operating handle, means interconnecting said handle and operating means, said interconnecting means including a lost motion connection to both the handle and operating means, an overcenter spring connected to said interconnecting means and movable through its dead center position to eflfect snap movement of the operating means, and means for efiecting movement of the point of spring connection to said interconnecting means when the spring has been operated to a predeter mined position, said movement throwing the spring through its dead center position independently oi further movementoi the parts and preventing maintenance of the parts in a semistable, dead center position.

3. In an electric switch, cooperating stationary and movable contacts, operating means connected to the movable contacts, an operating handle, means interconnecting said handle and operating means, said interconnecting means including a lost motion connection to both the handle and operating means, an over-center spring operatively connected to said interconnecting means by a pin and slot connection and movable through its dead center position to effect snap movement of the operating means and movable contacts, said slot being so directed with respect to the line of action of said overcenter spring as to efiect movement of the pin within. the slot when the spring has been operated to a predetermined position, said movement moving the spring throughits dead center position independently of further movement of the operating handle preventing maintenance of the parts in semi-stable, dead center position.

4. In an electric switch, cooperating stationary and movable contacts, operating means connected to the movable contacts, an operating handle, means interconnecting said handle and operating means, said interconnecting means including a lost motion connection to both the handle and operating means, an overcenter spring operatively connected to said interconnecting means through a pinand slot connection, with the slot being in the'form of an obtuse angle, the legs of the slot being so located' with respect to the line of action of the overcenter spring as to effect movement of the pin within the slot to throw the spring through its dead center position in both directions of movement as it approaches what would have been its dead center position without the pin and slot connection whereby the parts cannot be maintained in a semi-stable, dead center position.

5. In an electric switch, cooperating stationary and movable contacts, operating means connected to the movable contacts, an operating handle, means interconnecting said handle and operaitng means, said interconnecting means including a lost motion connection to at least the operating handle, a spring guide connected to said interconnecting means by a pin and slot connection at one end, guide means slidably receiving the other end of said spring guide, an overcenter spring mounted on said spring guide and movable through its dead center position to efiect snap movement of the operating'means and the. movable contacts, said slot being so directed with respect to the line of action of the spring as to effect movement of the pin within the slot to move'the spring through its dead center position independent of further movement of the operating handle when the spring has been moved to a predetermined position.

6. In an electric switch, cooperating stationary and movable contacts, operating means connected to the movable contacts, an operating han-' dle, means interconnecting said handle and operating means, said interconnecting means including a lost motion connection to at least the operating handle, a spring guide connected to said interconnecting means by a pin and slot connection at one end, pivotally mounted guide means slidably receiving the other end of said spring guide, an overcenter spring mounted on said spring guide and movable through its dead center position to efiect snap movement of the operating means and the movable contacts, said slot'being so directed with respect to the line 01' action of the spring as to eflect movement of the pin within the slot to vmove the spring through its dead center position independent of further movement of the operating handle when the spring has been. moved to a predetermined position.

7. In an electric switch, cooperating station ary and movable contacts, operating means connected to the movable contacts, an operating handle, means interconnecting said handle and operating means, said interconnecting means including a lost In tion connection to at least said operating handle, a spring guide connected at one end of said through a pin and slot connection, guide means for the opposite end of said spring guide, an

overcenter spring mounted on said spring guide and movable through itsdead center position to efiect snap movement of the operating means and movable contacts, said slot being in the form of an obtuse angle and serving to effect movement of thepoint of spring guide connec,

tion to the interconnecting means. so as to throw the overcenter spring through its dead center position independent of further movement of the operating handle when the spring has been operated to predetermined positions in both directions of operation of the switch.

8. In an electric switch, cooperating stationary and movable contacts, an operating handle, means for efiecting movement of the movable contact in response to movement of the operating handle, including an overcenter spring movable through its dead center position to effect snap movement of the movable contact, a pin and slot connection for one end of said overcenter spring, said slot being in the form of an obtuse angle, the legs of said angle being so related to the line of action oi the overcenter spring as to efiect movement of the spring through its dead center position independent of further movement of the operating handle when the spring has been moved to predetermined positions in both directions of operation of the switch.

9.'In an electric switch, cooperating stationary and movable contacts, an operating bail connected to the movable contacts, an operating handle, a freely pivoted member, means on said handle providing a lost motion connection to said freely pivoted member, means providing a lost motion connection between said freely pivoted member and said operating bail, an overcenter spring operatively connected to said freely pivoted member, and means for effecting movement of the point of spring connection to the member independent of further movement of the operating handle when the spring has been moved to a predetermined position, said independent movement of the point of spring connection moving the spring through its dead center position and preventing maintenance of the parts in a semi-stable, dead center position.

10. In an electric switch, cooperating stationary and movable contacts, an operating bail connected to the movable 'conltacts, an operating handle, a freely pivoted member, means on said handle providing a lost motion connection to said member, means providing a lost motion connection between said member and bail, a spring guide connected at one end of said member by a pin and slot connection, guide means for the opposite end of said spring guide, an.

overcenter spring mounted on said spring guide interconnecting means and movable through its dead center position to eflect sna movement of the operating bail and movable contacts, said slot being so related to the line of action of the overcenter spring as to effect movement of the pin within the slot to move the spring through its dead center position independent of movement of the member when the spring has been operated to a predetermined position. i

11. In an electric'switch, cooperating stationary and movable contacts, an operating bail connected to the movable contacts, an operat ing handle, a freely pivoted member, means on said handle providing a lost' motion connection to said member, means providing a lost motion connection between said member and hail, a

able through its dead center position to effect snap movement of the operating means and movable contacts, said slot having its defining edges. inclined to the line of action of the overcenter spring when in what would normally be its dead center position, whereby the pin will move within the slot as the spring approaches its normal dead center position'but prior to its arrival therein, movement of said pin within the slot effecting movement of the spring through-its dead center position independently of movement of the operating handle whereby to prevent maintenance of the parts ina semistable dead center position.

13. In an electric switch, cooperating stationary and movable -contacts, operating means connected to the movable contacts, an operating handle, means interconnecting said handle and said operating means, said interconnecting means including a lost motion connection to at least the operating handle, a s'pringguide connected to saidinterconnecting means by a pin and slot connection at one end, guide means slidably receiving the other end of said guide,

movement of the member when the spring has been operated to predetermined positions in both directions of operation of the switch.

' 12. -In an electric switch, cooperating stationary and movable contacts, operating means connected to the movable contacts, an operating handle, means interconnecting said handle and operating means, said interconnecting means including a lost motion connection to both handle and operating means, an overcenter spring operatively connected to said interconnectin means by a pin and slot connection and movan overcenter spring mounted on said spring guide and movable to its dead center position toefiect snap movement of the operating means and the movable contacts, at least the edge of said slot against which the pin bears being inclined with respect to the line of action of the spring in its normal dead center position whereby said pin moves within the slot as the spring approaches its dead center position, this movement of the pin efiecting movement of the spring through its dead center position independent of further movement of the operatin handle when the spring has been moved to apredetermined position,

, RALPH H. KINGDON. 

